1. Field of the Invention
The present invention relates to an image forming apparatus such as a scanner or the like which is used for a printer, a copying machine, an electronic filing system or the like, and more particularly to a discharge mechanism of a sheet material structured such that a sheet material such as a printing paper, a manuscript paper or the like can be quickly discharged to a recovering tray.
2. Description of the Prior Art
A scanner for reading a manuscript paper in an electronic filing system is divided broadly into a scanner structured such as to put the manuscript papers on a platen one by one and read an image thereof and a scanner structured such as to automatically supply the manuscript papers and read in series. In recent years, in order to effectively process a lot of documents, the latter automatic paper supply type is mainly used.
The automatic paper supply type scanner is basically structured such that the manuscript papers are picked up one by one from a paper supply tray for mounting the manuscript papers so as to be fed into a scanner main body and the manuscript papers are again discharged to the recovering tray arranged in an outer portion of the main body after being scanned by the image reading portion. Then, a feed roller for rotated for feeding and a guide roller for guiding a forward path are provided in a transfer path of the manuscript papers extending to the recovering tray from the paper supply tray via the image scanning portion. Further, a paper discharge mechanism for forcibly discharging the manuscript papers to the tray side is arranged in a portion corresponding to a terminal end of the transfer path and facing to the recovering tray.
The paper discharge mechanism is constituted by a pair of rollers for nipping upper and lower surfaces of the manuscript paper and is structured such that plural pairs of rollers are arranged in a widthwise direction at an interval. In this structure, any one of a pair of rollers is rotated and another thereof nips the manuscript paper as an idler so as to forcibly discharge the paper.
However, in the structure comprising the paper discharge roller rotated at the terminal end of the transfer path and the idler roller nipping the paper with respect to the paper discharge roller, a rear end of the paper to be discharged is not removed from the nip portion of the roller, so that there is frequently generated a paper jamming. The paper is not removed from the nip portion as mentioned above because the rear end of the paper is balanced in a state of being gripped in the nip between the rollers due to an empty weight of the paper at a time of being discharged upward, for example, as described in Japanese Patent Unexamined Publication No. 9-278147. Then, in addition to the upward paper discharge structure mentioned above, even in a structure of horizontally transferring the paper and discharging the paper in a horizontal direction toward the tray as it is, there is generated a trouble that the rear end of the paper is held by the paper discharge roller portion in the same manner.
With respect to the problems mentioned above, for example, in Japanese Patent Publication No. 8-18740, there is described a paper discharge mechanism which realizes a quick paper discharge. The paper discharge mechanism described in this publication is structured such that projections 52a are provided at a fixed circumferential pitch on peripheral surfaces at both ends in an axial direction of a paper discharge roller 52 coaxially arranged in a drive shaft 51, as shown in a schematic view showing a main portion of a prior art in FIG. 7. In this paper discharge mechanism, since a paper P can be discharged with engaging a rear end of the paper P with the projection 52a of the paper discharge roller 52, it is said that the mechanism is preferable for discharging the paper P.
However, since the paper P is nipped between the paper discharge roller 52 and the idler roller 53, a deformation D a little expanding upward is generated in the paper P due to protrusion of the projection 52a outward from the outer peripheral surface of the paper discharge roller 52. Since the deformation D is generated in a feeding direction of the paper P so as to form a stitch shape, the recovered paper P tends to be injured. Further, when the paper P is worn out so as to generate a small hole and an open seam, the projection 52a enters into the hole and open seam, so that there is a case that the paper is widely cut or broken.
As mentioned above, the conventional paper discharge mechanism can not avoid the deformation generating the recess on the paper and tends to injure or break the paper. Further, when the paper discharge roller is close to the image scanning portion, the recess deformation of the paper extends to the scanning area by the image scanning portion, so that an image reading on the manuscript paper is influenced.
In this case, the problems mentioned above are generated in the automatic paper supply type copying machine and the printer in the same manner in addition to the scanner apparatus.
An object of the present invention is to provide a discharge mechanism of a sheet material such as a paper which can quickly and securely discharge a paper after reading or forming an image to a tray in a recovery side with no deformation.
In accordance with the present invention, there is provided an image forming apparatus comprising:
a transfer path to which a sheet material is supplied;
an image processing apparatus for reading an image from the sheet material or printing an image on the sheet material, the image processing apparatus being arranged in the middle of the transfer path;
a tray arranged in a lower side of a terminal end of the transfer path in series and mounting and recovering the sheet material; and
a discharge mechanism for discharging the sheet material to the tray, the discharge mechanism being provided in a terminal end of the transfer path,
wherein the discharge mechanism is provided with a pair of discharge rollers arranged in upper and lower portions of a path line of the sheet material so that at least one of them can be driven and nipping the sheet so as to apply a transfer movement, and discharging means operating in such a manner as to interlock with the discharge rollers and forcibly pushing a rear end of the sheet so as to discharge to the tray side.
In accordance with a first aspect of the present invention, there is provided a discharge mechanism of a sheet material in an image forming apparatus comprising:
a transfer path to which a sheet material is supplied;
an image processing apparatus for reading an image from the sheet material or printing an image on the sheet material, the image processing apparatus being arranged in the middle of the transfer path;
a tray arranged in a lower side of a terminal end of the transfer path in series and mounting and recovering the sheet material; and
a discharge mechanism for discharging the sheet material to the tray, the discharge mechanism being provided in a terminal end of the transfer path,
wherein the discharge mechanism is provided with a pair of discharge rollers arranged in upper and lower portions of a path line of the sheet material so that at least one of them can be driven and nipping the sheet so as to apply a transfer movement, and discharging means operating in such a manner as to interlock with the discharge rollers and forcibly pushing a rear end of the sheet so as to discharge to the tray side. Accordingly, even when the sheet material stops in a state of being nipped between the discharge rollers or in an immediately downstream thereof, the sheet material is forcibly pushed out by the discharging means, so that there can be obtained an effect that the sheet material can be securely discharged to the tray side.
In accordance with a second aspect of the present invention, there is provided a discharge mechanism of a sheet material in an image forming apparatus as recited in the first aspect, wherein the discharging means is a roller-shaped profiling pusher coaxially connected to at least one of the pair of discharge rollers, the profiling pusher is provided with a body portion smaller than an outer diameter of the coaxially connected discharge roller and a protrusion formed on an outer peripheral surface of the body portion so as to have an uniform cross section in an axial direction and having a height crossing the path line, and at least the protrusion is set to be capable of being elastically deformed so as to be deformed in a profiling manner due to a reaction force from the sheet material during a time when the sheet material passes through a nip portion of the discharge roller and be restored after the sheet material passes therethrough, thereby capable of being engaged with a rear end of the sheet material. Accordingly, it is possible to push the sheet material so as to discharge by a simple structure that the protrusion is only provided on the peripheral surface of the body portion of the roller-shaped profiling pusher. Further, in the case of providing the profiling pusher in the discharge roller side in the lower side of the path line, since the protrusion of the profiling pusher downward urges the rear end of the sheet material while pushing, there can be obtained an effect that the sheet material can be quickly recovered in the tray side for a short time without floating up.
In accordance with a third aspect of the present invention, there is provided a discharge mechanism of a sheet material in an image forming apparatus as recited in the second aspect, wherein the body portion and the protrusion of the profiling pusher are integrally formed by a sponge obtained by foaming a polyurethane, and the protrusion has a cross sectional shape tapered toward a front end side thereof. Accordingly, since the body portion is made smaller than the paper discharge roller although being made of a sponge, an expanding deformation due to a centrifugal force at a rotating time can be restricted, it is possible to loosen the pushing force against the sheet material by the protrusion, and there can be achieved an effect that a profiling deformation can be easily obtained when the sheet material passes therethrough by forming the protrusion in the tapered cross sectional shape.